KVM: selftests: add shared hugetlbfs backing source type

[linux-2.6-microblaze.git] / tools / testing / selftests / kvm / lib / kvm_util.c

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 491be22..28e528c 100644 (file)
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -847,10 +847,30 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
        if (alignment > 1)
                region->mmap_size += alignment;
 
+       region->fd = -1;
+       if (backing_src_is_shared(src_type)) {
+               int memfd_flags = MFD_CLOEXEC;
+
+               if (src_type == VM_MEM_SRC_SHARED_HUGETLB)
+                       memfd_flags |= MFD_HUGETLB;
+
+               region->fd = memfd_create("kvm_selftest", memfd_flags);
+               TEST_ASSERT(region->fd != -1,
+                           "memfd_create failed, errno: %i", errno);
+
+               ret = ftruncate(region->fd, region->mmap_size);
+               TEST_ASSERT(ret == 0, "ftruncate failed, errno: %i", errno);
+
+               ret = fallocate(region->fd,
+                               FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0,
+                               region->mmap_size);
+               TEST_ASSERT(ret == 0, "fallocate failed, errno: %i", errno);
+       }
+
        region->mmap_start = mmap(NULL, region->mmap_size,
                                  PROT_READ | PROT_WRITE,
                                  vm_mem_backing_src_alias(src_type)->flag,
-                                 -1, 0);
+                                 region->fd, 0);
        TEST_ASSERT(region->mmap_start != MAP_FAILED,
                    "test_malloc failed, mmap_start: %p errno: %i",
                    region->mmap_start, errno);
@@ -888,6 +908,19 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
        vm_userspace_mem_region_gpa_insert(&vm->regions.gpa_tree, region);
        vm_userspace_mem_region_hva_insert(&vm->regions.hva_tree, region);
        hash_add(vm->regions.slot_hash, &region->slot_node, slot);
+
+       /* If shared memory, create an alias. */
+       if (region->fd >= 0) {
+               region->mmap_alias = mmap(NULL, region->mmap_size,
+                                         PROT_READ | PROT_WRITE,
+                                         vm_mem_backing_src_alias(src_type)->flag,
+                                         region->fd, 0);
+               TEST_ASSERT(region->mmap_alias != MAP_FAILED,
+                           "mmap of alias failed, errno: %i", errno);
+
+               /* Align host alias address */
+               region->host_alias = align(region->mmap_alias, alignment);
+       }
 }
 
 /*
@@ -1318,6 +1351,42 @@ vm_paddr_t addr_hva2gpa(struct kvm_vm *vm, void *hva)
        return -1;
 }
 
+/*
+ * Address VM physical to Host Virtual *alias*.
+ *
+ * Input Args:
+ *   vm - Virtual Machine
+ *   gpa - VM physical address
+ *
+ * Output Args: None
+ *
+ * Return:
+ *   Equivalent address within the host virtual *alias* area, or NULL
+ *   (without failing the test) if the guest memory is not shared (so
+ *   no alias exists).
+ *
+ * When vm_create() and related functions are called with a shared memory
+ * src_type, we also create a writable, shared alias mapping of the
+ * underlying guest memory. This allows the host to manipulate guest memory
+ * without mapping that memory in the guest's address space. And, for
+ * userfaultfd-based demand paging, we can do so without triggering userfaults.
+ */
+void *addr_gpa2alias(struct kvm_vm *vm, vm_paddr_t gpa)
+{
+       struct userspace_mem_region *region;
+       uintptr_t offset;
+
+       region = userspace_mem_region_find(vm, gpa, gpa);
+       if (!region)
+               return NULL;
+
+       if (!region->host_alias)
+               return NULL;
+
+       offset = gpa - region->region.guest_phys_addr;
+       return (void *) ((uintptr_t) region->host_alias + offset);
+}
+
 /*
  * VM Create IRQ Chip
  *